I have held back from posting as didn’t want to jinx it. Seems like the alternator replacement fixed the issues. There was a lot of oil, which I cleaned down and now need to get back under to see where it was coming from (assuming valve covers). I went to to the bracket gasket at the same time, but the oil was on top of the alternator and the oil hose bracket attaching to the alternator bracket had rounded bolts - good news is that it looks like has been changed already.

Now to work out why my battery light flicks on (has done it three times in the last month), for a fraction of a second.

Thanks for everyone’s help.