Yeah, fair point, it's not that user friendly. I use Halifax online, they offer some Vanguard EFTs, (VUKE, VGOV, VUSA and VFEM) and now they only charge £12.50 pa fees, plus dealing costs of £2.00 per deal if you use their regular dealing system, plus the Vanguard management fees. Iweb are amongst the cheapest, and are on the same platform as Halifax, so probably offer the same funds. I believe Iweb charge more for some corporate actions than Halifax. So, Iweb worked out cheapest for me (using last year's limit to the max, with a total portfolio of around 45k), but wasn't significantly cheaper than Halifax, and the transfer out charges from Halifax would have wiped out that savings for three or four years.
I didn't keep the spreadsheet that I did the calculations on, otherwise I would share it.