Holes in Chilli leaves???

[Mitzi]

It might still be growing?

[veggiechicken]

Doesn't look like Tomato Moth caterpillar - more like Small White?

[toomanytommytoes]

Cabbage looper?

[Mitzi]

The moths I saw were darkish brown, medium sized. No photos.

[Martin H]

There's an awful lot of darkish brown, medium sized moths with green caterpillars. But if I had to pick one possible suspect it would be the Silver Y. They come over here every year with their omniverous appetites and wanton reproductive habits. They carry on laying eggs and hatching caterpillars until the frost kills them off.
https://en.wikipedia.org/wiki/Silver_Y

[Mitzi]

To be honest I’m not as bothered by what they are as by what to do about them. Tomorrow is hacking down the overwinters day. Hope it works.

[Scarlet]

Knowing what they are helps with knowing how to deal with them....

...as you've only seen them now. I assume that it's something that has been laid in the soil to hatch out in spring - the indoor temps bringing them out early. It would be good to know how long they take to hatch/ what their life cycle is etc.
Getting rid of the soil would be your best bet.

[seasprout]

What about using some neem oil or something watered through the compost & over the leaves,no risk to other insects as they’re indoors,it would be a shame to lose the plants?

Jane, is is illegal to use Neem Oil in the UK. It is not a registered pesticide, it is In-fact illegal to own it or sell it as well.