but its the ability to finish that I struggle with.
Theres a joke there...
Anyway.
Right finishing a project can be achieved by not bothering to finish it. At least not straight away. Put it on the back burner so to speak and start another.
That project stalls, and you start another until you have 5 opr 7 waiting in the wings.
NOW you can finish the first one. You've started project 7 or so, hit that wall and are looking about for something else to do. So you potter about with the first, or third or whatever one(usually dependent on what tools you have littering the bench)
You have a creative mind, but are being held back by something like adhd or along those lines. Maybe undiagnosed or the need to find something exciting to fill a hole, which is the rush a new project gives you. But as you know, finishing the dam thing, especially if it takes longer than expected, is causing a problem. So getting lots of half/mostly unfinished projects sitting waiting is the best solution to this long known about problem.
You will find that 99% of all the great artists and designers have loads of half finished projects on the go. Unless you're working to specifics - for someone, or to achieve something that is really needed, those jobs you do in a oner, but stuff that pops into your head, its best to have lots of them.