Trivially small pension - what to do?

certainly look at youinvest, not sure if HL costs too much (from memory I thought they were expensive) (if you have a fund portal (say for ISAs) you may find that adding this SIPP will kick you into a lower management cost bracket so look at what you have first)

I'd go looking for funds that win every year for a minimum of past 5 years but more if possible.  You then want to look at annual gains, taking care to realise that the tables often say three year rates when they mean the rate for three years or the annual rate compound over three years.  The difference is massive.  I'd look for funds that have made, in the region of 13 to 15% every year for 5 to 10 years with low levels of standard deviation (so as straight lined as possible to sort out timing issues) I'd also try and avoid anything that does better than 20% a year, because sky rockets crash and timing on funds is not something most people are any good at.

The ones that jump up to me are Fundsmith (I think he has done 5 years now) and one of the LF Train ones.

There are some great tools to do this, Morningstar is probably the most famous, but actually difficult to use.  www.trustnet.com/ is my preffered one but use two.  You want one that takes you back at least 10 years because you want one of the ones that did ok in 2007 and still does well now.  You need two because not every fund is on every analysis website.

Out of these choose say 3 Funds, tops.  Review annually

I would suggest using the HL 150+ suite but not been impressed and have only one of those in my portfolio which has done well, the rest look a bit meh.

There is a lovely concept that "past performance is not evidence of future performance" and the whole "reversion to mean theory", my view is you have to look at the overall economics of your core funding, under Obama, medicare in the US did very well, under Pump I think it is more doubtful but insurance will do fine.

There is another issue about which country the fund should focus on.  Certainly if you choose Fundsmith, I'd look for another one to be global and one UK.  But there is an argument to be out of Sterling for the next 8 years or so.

Good luck

This should help:  monevator.com/compare-uk-cheapest-online-brokers/