Hi Guys,
First time posting on this, but have used it many times to solve problems on my many land rovers, im a novice with the Disco 2, i only have it 6 weeks, shes auto, leather n 7 seats, love it to bits n perfect for my newborn baby. My problem is difficulty in starting the last few days n sometimes it can take up to a half hour, theres a new noise from what looks like a pump or compressor just behind the air spring on the drivers rear wheel arch, maybe somebody could tell me what this is n could this be the cause of my issue?? Many thanks in advance for any advise

The unit under the rear driver's side wheel arch is the fuel filter. In my opinion it's a service item, I replace mine annually with a normal service.
The item which is making the whirring noise is usually the fuel pump which is located in the fuel tank. The noise isn't usually a problem unless it's excessive or becomes a screaming type noise. The pump can seem to "over-work" if it's having trouble pressurising the fuel supply due to a leak somewhere or because the system is drawing in air.
The Td5 engine is normally pretty good starting. Taking up to a half hour is somewhat excessive and could well be a fuel delivery problem. There's plenty here on the forum about poor starting behaviour on the Disco 2. Try the search facility at the top right of the window.
Even though you've already bought your D2, check out @neilly's excellent advice at:-
https://www.landyzone.co.uk/land-rover/handy-buying-alarm-info.311291/
It could well offer you some more advice about looking after your vehicle and also some things which you might need to address on the security front.

Check oil level, sounds like injector washers or seals