As far as which platform to use try
http://www.comparefundplatforms.com/
It enables you to do a comparison.
There is an excellent calculator that shows you actually how much these previously hidden trailing annual fees have been costing us. For example a fund of £100000 at 1.5% annual fee with an average investment return over 10 year will be costing you £24000. If you do not get the initial fee refunded then it would be more.
I would look at the platforms refunding all these charges and who just charge specific fees if you buy or sell.