Why do you want to by stocks via a unit trust? with all those extra platform charges?
iShares are ETF's that mirror a number of uk (and other indexes) they are brought via a broker like any other share or security.
Id also consider some of the UK investment trusts some of which have been running for 100's of years and have been paying dividends for decade upon decade.
I would investigate the various uk based dealers and pick one whose charges you like.
Money Observer, Investors chronicle would be a couple of good uk baseUK based magazines to read to do reserchresearch as is motley fool UK.