What WildBill and Gizzo said, except to point out that WB's favored Ozzie brand of Penrite oil can be VERY hard to find without having to dodge wallabies and then run a gauntlet of fetching Koalas with chlamydia in the parking lot. And that if you need to choose between a ⅜" or ¼" torque wrench, as Gizzo recommends, go for the smaller one. Many (though by no means all) of the ⅜" ones, particularly the less expensive brands, don't go right down into those single digit footpounds settings called for with certain Bullet fasteners. But in a pinch even a humble fish scale and some maths will do the job (With 12 inches to a foot, got a 6 inch long combination spanner? Pull it with the scale and double the reading. For a 4 incher "stubby" just treble it to find the FOOTpounds, OK?).
Also, those short "stubby spanners" I mentioned, and maybe a nice little stubby ratchet, are your new special friends, especially for reassembling or tightening, as is a medium threadlocker compound like "Loctite". Their smaller lengths will really help keep you from giving anything too much of a heave-ho and thereby stripping those sometimes fragile threads.
I agree that you shouldn't be intimidated by doing your own servicing. I would only add that for warranty purposes you should keep scrupulous records of your purchases and work. Receipts stapled or pasted into a notebook with dated descriptions with odometer readings of all work done on the bike written onto the facing pages might provide more convincing documentation for later warranty claims than an old sock stuffed full of Tesco receipts, if it came to that. Here in the States we have Federal Laws upholding our rights to splash used multigrade all over the family dog ourselves and not void the vehicle warranty, but yonder in your Sceptered Isle, where I presume you reside, I'm not quite so sure what the warranty rules are. Also, should you ever sell the bike, presenting such tidy records to a prospective buyer could only boost their confidence that the bike had been well cared for and fettled, and that you most likely hadn't just added whatever old chip oil was handy in the kitchen to the crankcase.
Also, if you're new to what we "Colonials" call "wrenching", you may be pleased to learn that the venerable British firm of Haynes has published a service manual for your ride, as found here on Amazon UK:
https://www.amazon.co.uk/Enfield-Bullet-Continental-Service-Repair/dp/1785214276, while the equally estimable Pete Snidal's Service Manual for your newer style of Unit Construction Engine (or "UCE") Bullet can be purchased here:
http://www.enfield.20m.com/uce1.htm. Both of these guides will have those all-important torque settings.
Oh, and welcome to the Horde of the Archaic!