Personally i would get the older sovereign. For the difference in price i will get what i want. The new sovereigns looks like a copper coin - they don't look right to me. So you pay more for what on this forum at least is almost universally accepted as the better looking coin - why wouldn't you be able to recoup that money on sale? If you plan to sell to a dealer then perhaps you won't but if you plan to sell to private individuals then i think you will.
The USD has been strengthening - this makes gold more expensive in GBP terms. There may be some strengthening of Sterling which will make your coin cheaper. You might say a bit but i think a regular purchase of coins means you gradually build up a stack and iron out the bumps in price.
These are just generic 'postcards' (blank on the reverse) they usually include in the envelope. 2 pages of bumph pumping the overpriced coin, then another page order form if you're daft enough, all on the fancy paper, and finally these little cards again with the 'great' offer. I collect all the little cards just to remind myself how much spam I've got to date, that's 13 wastes of paper now.
I might frame them up myself for a coin montage, or maybe just play a hand of snap when I get a full deck