Alfa Travel is independently owned and has been in business for 31 years. They made £1.15m profit in the last financial year, which was up 22.4% on the previous year's profit.
Sourced from here:
https://beta.companieshouse.gov.uk/company/02326610
They're members of ABTA, which is confirmed on ABTA's own website:
https://www.abta.com/abta-member-search/results?search=alfa+travel
So they should be totally safe to book with. (If you're still worried though, use a credit card to book with, rather than a debit card, as that provides you with extra cover in the event of anything going wrong).