If your soil is very alkaline then you are going to have a problem growing an acer in the ground as they need acidic soil. You would need to make a huge hole and fill this with ericaceous compost and keep adding more each year, even then once the roots grow out of the area where you put the compost they will not be happy. In this instance you might be better to have one of the small patio japanese acers and keep it in a pot. Remember it does not like full sun or wind.

As MG says, it would be very difficult to condition the soil over the entire future root area of the Acer.
One strategy could eventually get an Acer into the ground:
First, mark off an area with the appropriate sun exposure and wind protection, about 3 m wide in the smallest dimension. Resolve to grow only annuals and short-lived--or easy to tansplant--perennials in that area for the next 3 years. Cover the area with 2 cm of ericaceous compost, or 1 cm of composted dairy cow manure. Cover that with 5-8 cm of wood chip mulch. By late summer, if the rainfall has been good, pull aside the wood chips temporarily, and apply half as much compost or manure as above, then replace the chips. Repeat twice a year for the next two years. That should improve the soil pH and structure enough to allow an Acer to do reasonably well. Be sure to keep up the treatment once a year after the Acer is planted, to keep it healthy.

mmmm maybe I'll just pot it into a bigger pot! Thank you both.

Unfortunately it will be a lot easier in this case...

'Strooth!