TO follow up this thread - I have been driving around since I wrote it with no great inconvenience - the most difficult thing really has been getting used to starting the car more slowly and waiting for the electronic whurring of what I think is the petrol pump to stop before I start the engine.
If I do forget this and turn the key all the way without this pause occasionally the elecronics die. I have discovered the best and quickest way to remedy this is to disconnect/reconnect the battery positive - breaking the circuit for only a few seconds seems to restore the car electrical system to normal.
I remembered the batt. positive terminal connector has probably always been a bit loose since I gave someone a jump start so I've made a point of tightening it in case a poor contact is making it overload.
Indeed, could giving the jump start have buggered my battery slightly? I hope not, I will never be so kind again
Oh.... and what IS the whurring sound I hear when I first turn the key?
Thanks for everything.