When will quicken app be available UK?

I think it’s highly unlikely we'll see the mobile app in any app stores other than US and Canada unless Quicken decide to sell the product outside of those regions. It’s around fifteen years now since they withdrew from the UK market, and with the plethora of online banking options now available I'm not sure they would see it as worthwhile to try and re-enter the market, although it would be nice if they did.

If you’re using iOS, and are determined enough, you can sign into the US Apple App Store from the UK and download the Quicken Mobile app (google for details if you’re not sure how to do that). Once you have the app installed you can sign back into the UK App Store, but you’ll need to periodically switch back to the US store to get updates to the Quicken app.

Having the app is of little use if your accounts are in GBP, as "foreign currency" accounts (i.e. accounts not in USD) cannot be synchronised between the desktop and the app.  You can kludge around that by having an account in USD that you synchronise, and then cutting and pasting transactions between it and your "normal" accounts, but it’s a very clunky workaround that’s prone to error; personally I think it’s more trouble than it’s worth.