Best place for fairly high savings

The trend at the moment is for people to stash their cash in the top paying current accounts with all the high street banks. They all have 'must deposit £x per month' which you can achieve by setting up standing orders to cycle the money between the accounts, and the interest rates on offer vary from 3% on the first £20k of account balance at Santander (1.8% net to you as high rate taxpayer) up to 5% (3% net to you) on much smaller amounts at Nationwide or TSB, with others in between (4% gross at Lloyds on £5k)

A number of the banks let you have multiple accounts. So you could probably stash away most of your existing savings with that method and you would be earning a better overall rate than by using 'savings accounts' or cash ISAs.

There are some 'regular saver' accounts where you can put a maximum £x of new money per month and get a good rate. Nationwide will give you 2.5% gross on £1kpm, First Direct 6% on £300pm. This takes care of most of your new cash.

As you are spending £15k of your stash this year you'll still have enough headroom on all these schemes to keep using them for a good while. At the end of the tax year you might want to see what rates are available on ISAs to use up this year's ISA allowance before you lose it. It can be valuable in the longer term as a high rate taxpayer.

However, if a house deposit in another couple of years is a goal, you might not be able to max out multiple years' ISA allowances and so if current accounts and traditional savings pay better, you do not necessarily need to worry for this year and could just start to put some of your money into an ISA when you get around to it.

I'm assuming you like the idea of cash savings for your goal of saving another house deposit but if you will always have some longer term money in the background that you don't touch, you can consider stocks and shares ISAs.