@Stivy,
i am indeed a mad keen Sunderland supporter and have been ever since 196I, Sunderland V Spurs in an FA Cup match. Willie McPheat scoring for us.64,000 in Roker Park and I've been a stupid fan ever since, ,I ended up in Spain because my long term partner has severe arthritis and the weather here, way out in the sticks is so much kinder, the pace of life so less stressful. That big hot sun warming the bones.
I'll be honest the chances of having a successful olive harvest in the UK, either for the table or for oil, is something I just didn't think possible. However on consulting Google the arbequina variety is grown in the south of England, Suffolk, apparently and there's a claim that you can get up to 20 lbs a tree- (really?). I find that hard to believe . That sounds way, way optimistic.
However you must remember out of 1000 plus varieties some, like the ones I grow are for oil, and other varieties are for the table. I grow exclusively for the oil. My experience of table olives is that they need a lot of prolonged and repeated soaking in brine and it's a faff and hard to get right . You can't just pick an olive off the tree and have a munch by the way. They need curing. And again if you want edibles you need to identify what type of olive you are growing and see if it is suitable for the table as opposed to the mill.
Of course if you do grow for oil you have to have an olive mill within striking distance and here they will only take a minimum quantity of many 100's of kilos . Even with my trees, sufficient to say to get that quantity, I go in with a neighbour and we share the proceeds, I doubt if they are many olive mills around Sunderland- maybe in SR6 though?
So if it is possible it's the table varieties you need to go for.
I'd be fascinated to know how you get on. And if you aren't successful with a crop a well pruned olive tree is a beautiful thing to behold, just as specimens in their own right.
Best of luck.