Hargraves Lansdown do an account where it gives you loads of differing options , its called Active account where you are offered loads of different options from different suppliers , what you do is open an account with them and you choose which savings account/Isa is best for you and you then choose your option and they do the rest for you. i looked yesterday and the best cash Isa was 5.2% .
They don't charge commission or a trail fee they claim to get their cut from the banks you choose , there are several different suppliers offing similar services but fees may differ .
Check it out it may be for you , may not