If you don’t fancy mixing up sand and cement you could always just dig the hole out, position the y anchor with a few bricks to wedge it in position and then 2-3 bags of post-crete (£5 a bag). Really easy - pour the required amount of water in the hole, empty bags of post crete into hole, bit of prodding to make sure it’s all around the anchor and then top up with some more water. Goes off in about 15mins. Note sure how it would be as a slab to park the bike on top, but if you wanted to just take a few paving slabs up sink the anchor and then reposition the slabs (cut around the anchor) this would be really easy.
all sounds great. thank you very much.
i`d just remove one slab, dig down 9 inches and at the bottom of the hole dig under the surrounding slabs a bit so the hole is slightly tapered being wider at the bottom. then position the anchor in the centre and fill the whole area with concrete and smooth over flush level with the slabs using a float/trowel. couple or three bags of ballast/cement from b&q should do it.(get the stuff you have to mix as its stronger than the met post stuff) couple of hours work. if it looks like its gonna rain cover it and it should be set the next day. 
thanks for that one as well.
Ill get my mate to come over a take a look at in in the next few weeks better yet just show him the pictures. Know him he he will have a load of concert already. so should only really have to pay for the anchor and chain. and sort him out of course.
I should really learn how to do this stuff. dam
If your just looking to concrete the anchor in you probably best going with some bags of rapid setting ready mixed postcreate CLICKETY CLICK LINKY HERE
5 x 25kg bags for less than £20 
Edit: Whoops just seen Cooltempo post
Put loads of hardcore in the hole mate…And use Ballast not cement
Bought my anchor today went with PJB in the end as suggested. Hoping it comes soon. im now debating weather to get the chain this month or when im next paid… either way its all in motion 