To select a broker check the comparison on monevator. They also have a list of the best index passive funds. I mostly do vanguard, highest rate I have is 0,22% but also have some very low cost HSBC tracker funds at 0.06%.
I use Alliance Trust because they don't do % fees only fixed fees.
I use stocks and shares ISA via Bestinvest. I use a combination of tracker and managed funds on the basis that managed funds can be actively managed in a downturn and I also drip feed contributions to smooth out price drops/increases. I like their platform - it is easy to use and there is lots of advice but it is probably personal preference.