Experience of First Direct Offset?

IAMIAM

What is the difference between overpaying a lump sum and keeping the savings in an offset savings account. Does one reduce your monthly payment - or can it potentially?

Can you withdraw money instantly up to your LTV bracket (75%) if you say have borrowed 70% LTV or have overpaid?

Bluebell1000

A lump sum overpayment is usually not accessible. Money held in an offset is accessible up to the current value of that mortgage (e.g. if in repayment, you might only be able to access for example £90k of the original £100k mortgage, as some has been repaid via regular monthly payments). You can't withdraw to the max LTV, only the mortgage amount outstanding.

Putting overpayment into a standard mortgage can be a good thing if it removes the temptation to spend it! Depends on how you feel about planning savings to increase the offset to get it repaid / fully offset. Offset mortgages tend to be more variable in their monthly payments too, as offset reduces the interest payments you might find some months are higher (less offset) and some lower (more offset). 

We had a first direct offset a while ago and were very happy with it, but had to move away from them back to a standard mortgage when we moved, as we no longer met their criteria. If they'd not said no we'd have been happy to stay. If you are already approved you should be ok, but I think they are quite strict on affordability from our experience anyway (£600 a month in a regular saver was viewed as a committed outgoing and impacted affordability)!