Like Gillian, I have in the past made use of Free Weekends on Ancestry and also on Findmypast. I now have a subscription and find it invaluable for my research. I haven't had any problems with malware of any sort.
Like you,I use my local archives. Using local archives is great but not much use for research on individuals from the other side of the country. It is also true that many Archives and public libraries have a subscription to the Library edition of Ancestry and sometimes Findmypast. Again this is great, although there are many records not in these versions and for many people not convenient (may even cost more in transport and parking that a subscription)
Unfortunately, all local archives have limited funding (not a high priority in the eyes of many ratepayers) In some areas this has led to very restricted opening hours and even the proposal to charge (Northamptonshire, although the outcry led to at least a temporary withdrawal of the proposal) Unsurprisingly many of the archives have looked for other forms of funding. Many have received some heritage lottery funds but these are usually quite specific rather than general funding.
Many archives have also joined up with one of the large commercial sites to digitise and make available on those platforms various sets of records. The agreement usually seems to allow exclusive online access to these records on the 'partnership' platform for a period of time. Medway is no different. It formed a partnership with Ancestry in 2016 to digitise and index workhouse records from three poor law unions, and since then Methodist registers from the area. I see that there are also some Medway National school records on Findmypast . A large number of Kent parish registers are also on Findmypast.
Allson Cable, "MALSC's first project with Ancestry" The Clock Tower (Friends of Medway Archives and Local Studies Centre) Nov 2016 p8
National Schools Admission Registers, list of participating archives