Does any fellow GoYer grow Tomantillos?

Are you talking about the tamarillo or tree tomato...Cyphomandra betacea, or the tomatillo, physalis ixocarpa?
I've grown the first, but it required high temperatures, made a very leggy plant, and didn't produce any fruit until the second year in a frost free conservatory. After all that effort it tasted diabolical and the plant's leaves stink.
The physalis has to have the same treatment as the other physalises like the groundcherry or cape gooseberries, and the fruit is carried inside papery husks.
I think you'd be pushing it to grow it successfully in Scotland as the fruit is produced right at the end of the season, so even in a greenhouse it might be difficult with shortening days. I don't know if it's a perennial like the cape gooseberry as you can overwinter that by keeping the roots protected from the frost, and then start it back into growth in spring to fruit much earlier than from seed.
Worth having a go, perhaps. Good luck.

Oops typo there tomatillo Bertie. I've been googling on extensively and everything 'says' they are hardy even up here. I wont necessarily even grow them myself but do want to be honest in the book.

I've grown them, MG, and I treat them the same as tomatoes or peppers. They seem to be a little more heat tolerant than their cohorts, but don't particularly need the heat to fruit. Telling when to pick them is sometimes a head scratcher though. Pick them green for a tart salsa, or pick them ripe (orangish or purplish inside the husk) for a sweet sauce. The trouble comes with the varieties that stay green, like 'Toma Verde'.

Thanks Tugbrethil - having decided that that Chayote will not do in the UK or northern part of America this was my solution as a new(ish) unusual veg. Seed is readily available. Could you possibly pm me with any growing advice. Normally I'd would want to have grown for at least two years before writing about but haven't got that option this time round.