Very quick update. Thursday evening I took the loose front wheel to the MOT garage and Rose checked the balance on it. Said it was fine. When I was reinstalling I thought I'd rule out have been warped brake discs too, even though the look straight so left the brake pads pushed in when referring the tyre and rode part way to work like this on Friday morning. As soon as I reached 30mph+ wobble was still there, with no change.
On Friday morning I also emailed Dunlop, who rather surprisingly emailed me back within an hour and followed it up with a phone call. The chap said it sounded like a defective tyre and suggested I could try increasing the tyre pressure but didn't think it would work. He also said really the tyre shop needs to resolve this then take the issue up with Dunlop (suggested I look at Consumer Rights Act - which from what I can gather entitles me to a repair, replacement or refund as the issue was there from the moment the tyre was fitted & as far as possible I've ruled out mechanical issues with the bike - the chap in the tyre shop & MOT mechanic have both checked the front end over). Dunlop chap also asked I have the wheel alignment double checked again just to rule it out.
Friday evening I called into the MOT garage and had the alignment checked - all OK. Whilst there Rose said she had a spare tyre, that although was a slightly different size, would fit the rim and allow me to ride up the road near the tyre shop to see if it was the tyre or not.
Collected the tyre yesterday, took it to the tyre shop. They seemed reluctant to fit it, so I explained what Rose had said. They said it was up to me, so I said that it was actually up to them as having spoken to Dunlop I've been told the tyre shop needs to resolve this. The owner of the tyre shop did not like that and started saying I should purchase a new tyre then they could return the tyre back to Dunlop and wait for Dunlop to agree it's the tyre then refund me. When I said that's not what Dunlop said he was even less happy and said Dunlop's advice was wrong, I could have damaged the tyre, was costing them money by going in - I should be paying for them to refit the test tyre etc, at which point his daughter (who has been great) asked me to go back to reception and later apologised saying he's just an arse. Anyway, whilst I was waiting they found a used Metzeler tyre in the correct size and fitted that. I went for a good run on it and the issue has gone.
I've left the old tyre with them and got the used one on until I hear back from them.