Thanks for the advice, guys. Here's my plan of attack - please be brutally honest!
ROOM: 3.4M by 2.4M. (about 8 square metres). No skirting. New sub-floor of 80mm deep sand/cement laid 3 months ago (I don’t do ‘quick’). Not exactly square.
ME: Fussy, decent DIY skills but never laid floor tiles. I’m working alone
TILES: Polished granite 305x305x10 (Absolute black), 2mm bevel edge.
SCREED: SBR (Styrene Rubber Butadiene) if I can find it (PVA if I can’t).
ADHESIVE: Mapei Keraquick grey from Screwfix at £6.89/5kg (How many?)

GROUT: Mapei Ultracolour Plus in Black (or Anthracite?) at £10.99/5kgs (How many?)
1. Sweep and vacuum sub floor.
2. Apply a sealant, starting in the furthest corner from the door
3. Leave to dry – one hour. Breakfast.

4. Pour self-levelling screed, spreading with a steel float.
5. Leave to go off – overnight. Allow some ventilation.
6. Find centre of each wall and pop a chalk line to divide the room into quarters (each 2 sm)
7. Mix enough adhesive to cover about two metres.
8. Apply to area 1 (further from door) and spread with 10mm notched trowel (£6.99 Screwfix).
9. Using standard white cross spacers, lay first 15 tiles, starting at centre where lines cross (if I can still see them under the adhesive!) – leaving gaps by the two walls.
10 Check with level for even laying
11 Measure and cut wall-edge tiles on wet saw, and lay checking against the rest with a level
Stop for tea.

12 Repeat steps 7 to 11.
Stop for the day
13 Repeat steps 7 to 11.
Stop for tea
14 Repeat steps 7 to 11, cutting round doorway.
Leave 48 hours.
15 Grout the joints.
Thanks will be given for all input, as usual. I'd especially appreciate some guidance on quantities of adhesive and grout (If there is a 'standard' grout gap between 12 inch floor tiles, what is it? Otherwise, I'll use some I already have).
z