Hopefully this new deal, once finalised, will mean greater availability of UK food products (although it may be too much to hope for that they'll get any cheaper) again in Spain, and help British business, and vice versa which will be good for the UK consumer. Like pretty much everything else the Brexit promoters promised, all that cheap food never did seem to materialise and nor did it result in a bonfire of red tape for British exporters, in fact quite the opposite.

New food exports deal signals end to Brexit ‘sausage wars’ | Brexit | The Guardian

I have never encountered more market mayhem as a result of the UK becoming a non-EU entity for self-harm purposes only with no benefit whatsoever. I've even told my kids that they're banned from ordering from any non-EU online store nowadays because I don't want to deal with any parcel mayhem and extra costs (that the seller will of course inform my kids that is NOTHING to worry about!).

On a side note is M&S Food available across the peninsula? Have they always been available, are they winding down, or going in the opposite direction?

Just before anyone gets too excited please be aware that in the UK at the moment there is going to be a by election in a place called Makerfield. Andy Burnham who is the Labour Candidate is looking to win this seat which is hotly contested with Reform.If Burnham wins he will be looking to oust Starmer,after his miserable performance in the local elections.If Reform wins then they could well form the next government..
Labour has jumped the gun on the announcement of this agreement to try and tempt rejoiners to vote Labour but I understand that the EU is keeping its powder dry and at the very least is looking for a huge down payment as an insurance against Farage reneging on the deal

Well look on the bright side, we can always stock up between 2027 and 2029.