£100 per month where to put it?

Cash ISA is not going to get you a return that beats inflation over the 20 years until you draw your employer's pension or the 30+ years til you can take the state pension. This month's £100 plus savings interest won't go very far in the year 2034 or 2050 or 2070.

So your practical options are S&S ISA or pension. Private pensions can hold the exact same investment options as S&S ISAs.

With a pension there is an additional tax break but the downside is you can't touch it for the next 20+years. If you are going to retire at 55 and wait a long time for state pension to kick in while you're only earning 8000 a year, you are 'wasting' some of your nil rate band every year (i.e. people can earn a few thousand over 8000 before paying tax). So getting tax relief now in a pension to deliver a small taxed income in retirement is a pretty good wheeze when the tax rate on your small taxed income in retirement is only nil percent. So, extra pension contributions are quite efficient.

Depending on your scheme at work, it might be possible to buy 'extra years worth' of company pension or to simply make additional contributions that grow as a separate pot on the side. Or contribute to a completely separate private personal pension.

S&S ISA will be less tax efficient because you don't get tax relief now (i.e. you make the investments out of income that's already been taxed). However, you never pay any tax in the future when you take income or capital out to spend, whereas on a pension you get tax relief now and a 25% tax free lump sum and pay tax on the other 75%.

Some people would hedge their bets and do a bit in S&S ISA (giving flexibility to spend it before they're 55, and to have a tax free income once they become a taxpayer after they're getting state pension and employer pension in their 60s) AND some extra pension contribution to get tax relief now and deliver an income between 55 and 65 that technically gets taxed but in practice will fit into the nil rate band while you're a low earner.

So, you might like to consider splitting the £100pm and doing most of it into pension (to draw out while waiting for state pension to kick in) and then a bit in S&S ISA too, which can be accessed in the shorter term if you need it or else left to give you a small tax free income when everything else is getting taxed in your 70s.

The other 'tax efficient' investment schemes like VCTs are not suitable for £100pm so you are pretty much just looking at the options outlined above.

Yes you are missing something. A 3% ISA when inflation is 1.5% or 2% is inflation beating, sure. When inflation is 3%+, it is inflation losing. Sometimes savings can pay a little more than inflation. In the long term they can't, because banks have no incentive to give you back any more than you gave them, if you're not going to let them take any risk with your money and earn a decent return that allows them to profit.

At the moment, cash ISAs without a multi-year lock in are paying well under 3% and your personalised rate of inflation (not the one the government quotes, which excludes housing costs etc and presumes you're an "average" person is probably just as much as that.

So, you can try to get an interest rate above inflation, but long term, you won't make it. Simple economics. And if you only equal inflation and don't beat it, you can't spend any of the interest earned, because you need every penny of the interest to try to preserve your capital in real terms.

The reason your pension conditions have changed for the worse a few times is that before, the return they were trying to get for you was unrealistic. With people living longer, the amount of money being put away to give you that return needs to be much more. If you start taking £8k a year from the age of 55 to 105, maybe increasing with inflation, you need a phenomenal amount of money in the pot.So it's not surprising they have been asking for more from you and haven't been able to offer more by the end.

Still, those "worsening" pension terms from your employer just illustrate how difficult it is to get a decent return in real terms that will last you for a decent amount of time. They are taking a whole chunk of money from you, out of your gross salary that hasn't even been taxed, AND the employer is putting a hell of a lot of their own money in too AND they are investing in a mixture of investment funds (shares and bonds) to try to deliver a better return than inflation over the long term - should be several percent a year better than cash... And still you probably don't think it's a fantastic amount of money at the end.

So, your idea that just by putting a small amount of net pay, after tax, into a cash ISA that barely covers inflation, is somehow going to get you something meaningful at the end, is laughable really. No offence intended but when you see the returns, you will have to laugh, otherwise you'll just cry.

With a 20-30 year timescale you must look at investment (either in S&S ISAs, or in a personal pension), if you want to turn the money into something meaningful. If you just want to keep a few thousand in cash for a rainy day, then cash savings accounts (ISA or non ISA, whatever pays the best net after tax from time to time) are perfect. But 20 years is not a "rainy day fund" type of timeline. Over that length of time, you should aim to grow your money, through INVESTMENT, not save for a rainy day, in SAVINGS.