Starting out

Hello to all members,

I am a newby.  I live in East Anglia, near Colchester, Essex.  I am about to try and set up my 1.2 Channel Master (Andrews) with a new H-H 1224 Supermount motor.  Question; I have worked out my site location, with SatSigs calculator and came up with 51.9290 N - 0.7179 E looking at Hotbird 13E.  When I double checked my location via post code, I got 51.9282 N - 0.720385 E.  Are the lat and long that critical? or will my previous location be OK?  I used the SatSig map for the first position. 
At present the dish is moved by 24" Jaeger but I am finding I have to re-correct the dish position on my receiver.  My system is approx 7 years old, and the polar mount is a bit rusty with a bit too much movement.
Any/all advice appreciated.

Thank you in advance,

Mikale

System; Echostar 3600VIA, 1.2 C.M. dish, + D.C.+loader, D2Mac,