So to sum up where I am so far. Garage were getting same problems as me last Wednesday but didn't have time to look at it. Came out to it Thursday morning and the car started straight away. All the dash error lights were on so they scanned the car and came up with a number of faults as mentioned earlier in thread. They cleared them and the car starts and runs fine and has continued to do since then (the lad has been taking it on road tests to try and get the same issues).
I said could they get their auto electrician to go over the car and try and find the issue. He has finally had chance this morning and can find no issues whatsoever. So getting the car back later today.
Not sure what has caused the issue, whether due to the amount of rain, water had got in somewhere. Remains to be seen whether it will come back to bite me in the coming days/weeks....