I'm fairly sure they don't need Maths for Geography at Bristol as DD was offered a place (within 24 hours) last cycle without it (no Science subject either). She applied for the 4-year programme with a year overseas in the third year. But Geog is a BSc at Bristol with an emphasis on quantitative methods. I think it was A, A, A needed for Bristol.
OP - you could have a look at the Complete University Guide (search Geog courses) to get an idea of the most popular / well-regarded Geography degrees.
Basically, they need A star, A, A predicted to apply for Cambridge, Oxford or Durham (but realistically most successful students will have higher predictions than this).
Cambridge and Oxford both offer courses that cover physical and human modules to begin with - but there are opportunities to specialise as the course goes on (or not).
Durham offer a BA (more Human Geog) or BSc (more Physical Geog).
UCL also offer a BSc or a BA, but they make little distinction between the two as it depends on the modules they choose once there and whether they prefer to graduate with a BSc or BA. UCL also offer a 4-year course where they spend a year abroad. I think the minimum grade threshold is A, A, A for UCL.
Another respected course is LSE where it is a purely Human Geography BA (again, A, A, A).
Exeter Uni have various Geography courses, inc a 4-year International Programme. Courses are offered on the Exeter campus or the one in Penryn, Cornwall (less competitive).
I believe Lancaster Uni offer a purely Human Geog degree? It might be something like A, B, B there?
Apart from these, Bath Uni offer a course called 'International Development with Economics' which, when you look at the modules, it very similar to a Human Geography BA. This course also has the option of an international year (work placement or uni).
Warwick do not offer Geography at all.
DD is at Cambridge and, like your DS, thought she would only opt for the Human Geog modules but actually, this has not been the case as the course encourages linked perspectives. It is hard work but fascinating and they frequently have guest speakers in the Cambridge Union who are at the forefront of research - eg. Danny Dorling was there recently and so was Brian Cox (I know he's a physicist, but still).