Closing US IRA

Does anyone have experience or advice about what to do with a US IRA?

I had a 401(k) that has since rolled over into an IRA.  It only has about $3000, so not all that much really.

Is it better to leave it as it is until I retire (loooong way away) or take the penalty and close it and shove the remainder of the money after penalties/taxes into my ISA where I have a much better interest rate.

I believe I would get a 10% penalty for early withdrawing and would be taxed as well (I believe the tax would be from the UK not the US due to a tax treaty)?

If anyone has done so, or seriously thought about doing so and knows a bit more about it, I would greatly appreciate your thoughts.

TIA!

You should be able to get a better rate on your IRA than on an ISA if you are investing for the long term. Personally I would leave it as paying a penalty early isn't something I'd ever want to do unless I was in an emergency situation.