Be very careful if you decide to look stuff up online - the treatments for several blood cancers have been transformed for the better in the last couple of decades but there is still older, scarier stuff out there. Not what you need to be seeing fight now. So stick to reliable sites, such as Bloodwise
This bit, at the very beginning, when you know it’s rather likely something is badly wrong but you don’t know what you’re up against, is one of the most stressful times there is.
I think you need to ask why it is these two conditions they suspect (and whether here is anything else it could be) and what they are seeking to establish by further tests. Are they near-near-as-dammit sure already, but need to confirm (or confirm extent) or are they really still investigating?
What tests do they want to run, what info do they hope to get from each?
They might want to do some - such as bone marrow biopsy - on the spot. For lymphoma, they will want to biopsy suspicious nodes. It can take a couple of weeks to get results back (they often need to grow cell lines) so find out when his gone, and how he finds out. Expect further bloods, and quite likely to be referred for scans
Ask what are the likeliest scenarios on results so far. What (in broad terms) are the treatment options and prognoses?
Does the unit have specialist nurses you can contact between times if questions come up or you realise you don’t understand something? Can they recommend reliable websites if you/he wants to read up? Is there s local cancer support centre or Macmillan office?
Take a notebook and pen, decide before you go in if you if he will make notes, get as many useful phone numbers as you can (at least the receptionist)
How long until the appointment?