Hello @user104759 and thank you for your interest in Espruino!
'looking to connect to external bluetooth device'
'what board would it be best to use'
It would be nice to know a bit more on what is to be accomplished. If one has a desire to attach other peripheral devices such as a temperature module or GPS unit, then I highly recommend the MDBT42Q breakout board for easy connectivity. If you need a viewable screen, the Pixl is ready to go there. Or maybe just a small 36mm or 1.5" diameter pendant button, then take a look at the Puck.
or estimated deliverable in March 2020 the First Programmable Watch Bangle.js
Take a peek at the 100+ (and growing) tutorials to get the juices flowing:
'i been messing about with arduino for years'
You don't have to apologize, we'll still welcome ya ;-)
I just jumped in two years ago with the purchase of the Pico (now I have 'em all) without the foggiest of where I wanted to go. The WebIDE is easy and intuitive and you will love the ease of real-time debugging/update without having to sit and wait for a compile process to complete. Having a breakout board makes life easier for connectivity.
Read over the forums to see what other are doing:
Tell us a bit more . . . . better yet, just get started!!
If so what board would it be best to use I am guessing it will be a MDBT42Q
Any help would be greatly appricated