@ItsOnlyWordsInnit - it's mostly online. I'm in Scotland and we are still under fairly strict pandemic restrictions in some areas. I was in the archives in Edinburgh about 4 weeks ago, my slot had to be booked 4 weeks in advance, papers quarantined before accessing, sanitiser, masks etc etc etc. So frustrating.
I am in several WhatsApp groups with other genealogists and there are often posts with "i'm in the National Archives if anyone needs a look up" or similar. It really depends what sort of research you are doing, most customers are just interested in the first few generations back, so I don't need to go to the national records of Scotland to pore over old medieval records.
On the lying - no, I don't think registrars were that bothered. I was in a very interesting talk a few months ago by a former registrar who is now a genealogist and he said that registrars are not allowed to challenge. If someone says they are 32, then that's what they write down. The exception to this is checking documents for marriage or whatever but they have to take other information at face value. I think there is a penalty for making false declarations but the registrar doesn't enforce that. I have recently come across a very sad case of a woman registering the death of her child twice within 5 weeks at the same registry office. She was in the workhouse and obviously not in a good place, she must have just gone along with what the officials told her to do. So the same child has 2 separate death certificates.
Lying on census about your age is SO common. People who age 7 or 8 years in the 10 years between each census. I don't think wanting to appear younger than you are is a 21st century thing. In my own tree, my ggrandmother was 2 years older than my ggrandfather and consistently changed her age to make him the older one. Perhaps they weren't that bothered. Also pre-1837 in England there would have been no birth certificates so it's quite possible people genuinely didn;t know.
DNA ethnicity estimates are notoriously inaccurate, especially with a small island like ours with people moving around. My gut feeling is that your "scottish" DNA is as likely to be Irish, especially in Lancashire. All those Ulster Scots who were put into Northern Ireland and then moved back in the famine for jobs in the mills. It's really not an exact science - my paternal ancestry is right on the English/Scottish border and I'm as much Nortumbrian as I am Scottish. But according to Ancestry, I have 0% English DNA.
I have uploaded my own DNA from Ancestry into MyHeritage and Gedmatch but it has only given me a few extra very distant relatives. And there are some privacy issues you have to be aware of, especially with Gedmatch. I'd always advise exploiting everything Ancestry has to offer first especially in the UK as they have the biggest database of UK test takers.