There are 4 wills for Thompsons of Ballyutoag on the PRONI wills site: Elizabeth d 1908, John d 1936, Mgt d 1884 and Wm died 1933. Only Margaret’s is on-line. For the other 3 you would need to look them up in PRONI.
No trace of a marriage between Allen Thompson and anyone after 1st April 1845 in the stat records, so presumably he married before that. His religious denomination on the 1901 census is “United F Church” ie United Free Church which was one of the secession Presbyterian Churches (following the great disruption as it was often called which split Presbyterianism in the 1830s). I can’t say for certain where he would have worshipped but my guess is to look at the parish records for Templepatrick Non Subscribing Presbyterian church. You would hopefully find all his children baptised there. However you might not get his marriage unless his bride was of the same denomination and church. Tradition was to marry in the bride’s church. So if she came from elsewhere, then her church is where they likely married.
Templepatrick NSP records have been copied and can be seen in PRONI, Belfast. They start in 1796.
Griffiths Valuation has Allen Thompson listed in Ballyutoag in 1861 (plot 48) where he had a farm, outbuildings and 28 acres. His landlord was Viscount Templetown. It might be worth checking the Registry of Deeds records and also Encumbered Estates records to see if any deeds or leases are registered. These can often name next of kin and descendants (especially in the case of a 3 lives lease). You can access these at PRONI, plus the Encumbered Estates records are on-line on findmypast.ie (pay to view).