ISA Full - choosing an Investment Trust!?

If you want passive investments have you considered etf's or why not stick to the funds you are already familiar with - you can hold them outside an isa - probably on the same platform you are using for your isa.
I would never buy into a IT unless it was on a decent discount.

IMO the LS100% is very light on smaller companies and also a bit light on Emerging Markets so, as these 2 areas have recently sold off but now starting to rise again, it may be an idea to use an IT to buy into one or both areas to balance the mix.

I would choose a provider who offered a range of different IT options within the one account so Aberdeen would probably be top of my list as they are EM specialists but also have some decent smaller company ITs on offer.

Depending on how much per month you want to invest I would probably go for EM first and build a decent position whilst this market is rising and then move into smaller companies in about 12 months when they should be rising again.

Just my opinion though

Is there a reason why you particularly want an IT? I'd suggest you first decide what you want to invest in and only then decide on the best way to do that.

A few years ago when there were still decent discounts to be had, I made a lot of posts suggesting people considered ITs. To some extent that ship has sailed, and while many reasons to consider IT's remain, I find myself in the odd position of being in the cautious camp: particularly with many ITs on a historically narrow discounts or even premiums.

I get the impression that some recent new buyers have been looking only at the increasing share price driven in part by narrowing discounts, rather than looking at the underlying NAV. They may be ignoring that discounts move both ways so boosting share prices in a bull market but increasing losses when they turn. The use of leverage that ITs can employ is two edged too.

There have also been changes in relative costs between ITs and UTs, particularly since RDR, so that in some cases the cost advantage of ITs, especially taking into account performance fees, has reduced or in some cases reversed. Popular managers running both ITs and UTs like Neil Woodford and Nick Train now have OEICs with OCFs of 0.60% or less so don't assume ITs will always be cheaper and make comparisons.

That said, with everything equal, my preference is for ITs, just not at current prices (with possibly a few exceptions). Some ITs have buying schemes but the disadvantage is that you usually won't know the price in advance and buy blind. I don't see much point in them when stockbrokers like SVS charge just over a fiver a trade with no account charges.

So certainly consider ITs but do your homework first and understand how they differ from OEICs/UTs.

As part of a portfolio of ITs/ETFs/Vanguard funds, you could consider Personal Assets Trust. It aims to attenuate market collapses, recently its %age in equities was only 44%, and then shift into equities to capture the upswings. In other words, it's an active investor, which you might like to balance any passive funds that just track the market. It has a discount control mechanism that means it always trades at round about zero discount. They offer a zero charge ISA and Investment Scheme, so the only charge you pay is the unavoidable stamp duty to HM Treasury.