So I've had my mavic almost a year now and I'll be very honest, I haven't used it half enough as I'd have liked! I spend alot of time working and then by the time my days off come I can never think of anywhere worth going to shoot! I don't drive and get around via train and I'm based in Liverpool! I was wondering if any of you guys had any recommendations on where I could go to fly or how to find decent spots myself? Thank you guys!

One thing you might try is to look at Google Earth around areas of your train.  Often times, I find interesting subject areas that way.

Get on the Wirral line and go to New Brighton. Some great scenery and the coast line at the mouth of the Mersey River has a light house, Fort Perch and other attractions you can take great video and stills of. I've done it a few times with the Mavic and my previous drones.

http://www.visitnewbrighton.com/

You also get plenty of ships coming in and out that would make a great subject plus the off shore wind farm, bit of flying needed but do able with the Mavic. ... just be careful of the wind if you do.
Going a little further up the coast line on the Dee Estuary side puts you into West Kirby, Hoylake, Parkgate etc. ... plenty to be going at there. On the Mersey side of the Wirral you have Birkenhead, Tranmere and the Ship Yards Cammel Laird.

Just be careful of flights coming from and going to Liverpool Airport, sometimes they fly in over New Brighton, depends on flight paths.

In addition to the great info Bigga J has kindly given you I'd also suggest downloading NATS drone Assist onto your mobile - this provides bang up to date information on no fly zones to help you assess if a precise location is off limits.

Hope other users might help to provide you with some recommended locations. And for me, I would like to advise you to check if there are any No Fly Zones around, make sure that you are permitted to fly there. https://www.dji.com/flysafe?site=brandsite&from=footer

Not familiar with your region

Beaches, parks, open country fields, riverbeds, abandoned farms - buildings - industrial sites .......just to name a few. Hope this gets the wheels turning.