Polish for what purpose?
If you're looking to improve the shine on the paint, you're not really looking to polish.
If you're looking to improve the feel of the paint, you're not really looking at polish.
If you're looking to touch up very minor paint imperfections - then yes, polish.
The Halfords BOGOF is indeed in full swing, and so let's keep this discussion to the products available there just to save some pennies (I emptied my local branch of several products earlier today
Autoglym Super Resin Polish is indeed a fine product, so I would say get hold of some of that. This is a true polish - lots of fillers and a little 'cut' to help mask fine scratches.
If you're looking to protect, get some Autoglym Extra Gloss Protection. This is a good quality synthetic sealant which is a doddle to apply and has very good results.
If you're looking to really get the look - and on black this is always tempting - then invest in some Autoglym High Definition Wax. At £20-£30 a pot before the BOGOF it's pricey, but worth it. This will really bring on the shine, and also protect the finish.
If you're after speed and ease - try some Autoglym Ultra Deep Shine. This is the sort of all in one protection product - but I don't rate it anywhere nearly as high as the other AG products.
For speed there's also Aquaxwax, which is ok and has its place - but I find it better for topping up existing protection rather than creating new protection.
I've today purchased some Megs NXT spray wax to try as a top up wax, so will report back on that in due course.
Hey, look folks - a whole detailing post from me and I didn't mention Dodo Juice once!