Newbie advice please

[reyno_gr]

I'm about to prepare a pit to partially sink my hot tub (Hydropool model 575) into the ground. I've read all the debates about above ground vs sunk into the ground, but the size of the garden necessities it (I don't want it to be the dominant feature). I know I need to have a 4" concrete base and good pit drainage (I live in the UK so there will only be two days in the year when its not raining). My garden is very small with restricted access.
I've been told I need a gap (access channel) of at least 60cm / 23" all the way round  the edge of the hot tub so the engineer can access it if it goes wrong. My questions are:
1. Is 60cm /23" an absolute minimum or could I get away with less? Can an empty spa be pushed across level concrete to create more space down one side if needed?
2. The hot tub is going into turf by a slabbed patio. I'd like to use similar slabs (for visual continuity) around the tub. Obviously I can't lay them as normal because that would prevent access to the access channel when its needed. Has anyone tried laying slabs onto a timber frame so they can be lifted to create an access hatch?
3. Plan 'B' - Does anyone have an ideas on the best way to 'lift' the tub out (if the right size access channel can't be achieved). Lifting webs left underneath, is a possibility but there is no access to the garden and I'd have to hire a crane (expensive) to do the job. I'll have to install it this way too!
4. Does the use of scents / scented crystals in a tub affect the filter or require more frequent water changes?
Any advice (other than buy a house with a bigger garden) gratefully received.Thanks.
Guy

[Flyonthewall]

i am no vault expert, but i have encountered many of them.  the drainage aspect cannot be stressed enough.  you cannot rely on drains.  they will clog up.  a submersible pump is the only way to be safe, and that needs to be tested frequently.  personally i hate that risk, so i would try to enclose it on 3 sides, while leaving the open side out of view.  the vaults i've seen all have the slab you mention, and also have block walls around the perimeter.  i've never seen one leave anything close to a 23" space between spa and walls except on the equipment side.  you would cap it to avoid people stumbling in?  standard vaults i've seen leave a 1-2" gap on the 3 sides, and are lowered in place by crane or with 4 men using 2 straps.  the method for getting the straps in/out is place a 4-6 inch block under the edge of the spa by the equipment.  if putting the straps under for extraction thread a strap underneath and see-saw it back and forth until you pull it to abouts 2/3rds of the way back.  repeat with a 2nd strap at 1/3 back.  then lift it out or attach to crane boom.  its not easy but 4 strong backs can do it.  i've been involved in the lowering in side, and my less than strong back did ok.