Well this has been fun....
Seems that the entire kitchen was built around the incumbent washer being in situ. Couldn't get the legs to retract as they were wedged in at the back, so had to cut them off with a hacksaw from underneath to get it out due to the floor being a lower level (dishwasher on the floorboards vs the tiles and layer of plywood in front of it.
Thought that would be the end of it, but had to drill through the kitchen unit next to it, where the power socket was oddly placed for it, as the new one has a moulded plug vs the old one which didn't.
I haven't been able to plumb it in because the new machine has a leak stop thing which attaches to the water inlet, however it is so big and chunky it won't fit where the pipework is due to the stop tap being in the way. So I need an extension pipe for that.
And as expected the fixings for the back of the facia are in different places - This was 99% going to be the case. There should probably be an ISO for that.
I can't help but think if I had paid for an install that they would probably have packed up and said "non standard, not doing it" and left me to it anyway.
So no machine until I get my extension pipe, but I'll get there. Wish I had just replaced with a free standing though

When it is finished I will likely be pleased not to have spent the £110. It's only been about an hours work.