Gatwick to Heathrow

If you aren't using a taxi, most people would suggest using the direct bus service between those two airports, as rail routes all require potentially inconvenient changes. The buses are long-distance ones with baggage compartments, and there will usually be staff available to help with loading/unloading. You won't be clinging on to a suitcase on an urban-style bus.

The pods are £5 each to ride in so a bit pricey, especially when you aren't getting to the terminal you want directly although maybe you'd like the novelty. You could get a bus to T5 for free (423).

Thank you both for responding and will look further into taking the buses.

Kind Regards,
Vickie

Transit journey planner:
http://www.tfl.gov.uk/plan-a-journey/results?IsAsync=true&JpType=publictransport&From=Gatwick+Airport&FromGeolocation=&ToGeolocation=&ViaGeolocation=&To=Thistle+London&TimeIs=departing&Date=20140903&Time=1930&Via=&NationalSearch=false&JourneyPreference=leasttime&Mode=tube&Mode=bus&Mode=dlr&Mode=river-bus&Mode=tram&Mode=cable-car&Mode=overground&Mode=national-rail&Mode=coach&AccessibilityPreference=norequirements&WalkingSpeed=average&MaxWalkingMinutes=40&CyclePreference=AllTheWay&SavePreferences=false&FromId=1001114

25 mins
national-rail
Southern to Clapham Junction Rail Station

21 mins
national-rail
South West Trains to Feltham Rail Station

16 mins
bus
285 bus to Mondial Way

6 mins
bus
81 bus or 423 bus to Heathrow Park Thistle Hotel

4 mins
walking
Walk to Hillingdon, Thistle London Heathrow (Visit Britain Assessed)

There is absolutely no point in using the TFL journey planner, as Gatwick Airport is well outside the TFL area and the journey planner does not cover long-distance coach services. You can find details of direct services at www.nationalexpress.com

TfL planner does go out as far as Gatwick, but this just illustrates that the journey requires several changes and is under usual circumstances longer.