Any dish will work for both if aligned on Astra 2. The LNB is the issue (the bit on the end of the arm that the cables connect to).
$ky dish and $ky hybrid LNB has 2 wideband (Q style) and four legacy (Sky+ style). Cables will need moving from one output socket type to the other when you change. Or you can plan ahead and install 4 cables to the one location (2x wideband, 2x legacy).
Insist on WF100 or similar all copper cable on the install (Q goes higher frequency and thin WF65 won't cut it in many cases). All copper is worth the very small premium over cheaper alternatives.
If planning on going Q $ky will install a wideband LNB for free when the time comes on a $ky type dish, including new cable if it is required.
Non-$ky dish (circular rather than oval) will be a bit more difficult and expensive to solve.
The most difficult place to maintain and uglier than one almost anywhere else in my opinion!
Most chimneys are really not designed for the added wind loading of a dish, either (especially when coupled with a UHF TV aerial)!
Dish on wall needs to see 28.2 degrees East of due South. (SSE) so only if the front of the house is south-facing and terraced need it go there.
Ground mounts can be 'hidden' behind regularly trimmed hedging or low wall or fence. Even a pole on the rear wall to peek over the ridge of the roof is an option that hides it from the road view.
$ky 60cm are Zone 2 not Zone 1 btw and is probably wise with a 6-output lnb.