ISA season, have a look and see if anywhere is offering a decent ISA rate. Savings should always be in a tax free environment first and foremost unless even after tax the NET rate beats the Gross rate (or should I say headline) rate of the other product. Bear in mind on non ISA accounts basic rate tax is deducted at 20%. If you are a higher rate tax payer there may well be further tax to pay over and above.
Given you are building a set amount each month, (lets say £500) you cannot go for a bond where the payment has to go in as a lump sum and come out the other end with interest. You are thus looking for an Instant Access type savings product, probably an ISA.
Bear in mind some personal current accounts offer gross rates of 3% upwards but you have to pay £x in per month but you can open up say 5 of them and transact, operate the account in such a way to meet the banks criteria. However, its an awful lot of hassle for not a great amount more tbh unless you are into the tens of thousand or hundreds of thousand and millions the actual rate doesn't in absolute terms make a huge difference and if you have sums like that, you'll be holding fixed term accounts, GILTs, Stocks and Shares etc.
On balance, Instant Access ISA would be just the thing.