Can i see an oncologist/hematologist with suspicion of lymphoma or do i have to be referred by gp?

Suspicion?: "have to" is more likely an insurance question rather than a medical q. Having your gp talk to an oncologist is the easiest solution. Lymphadenopathy (lad) has many potential causes -- eg see table 3 - LAD a-z. "lymphadenopathy" habermann & steensma - http://www.Matheny.Info/files/habermann_mayo_clin_proc_2000_75_723.Pdf - usually a DX is made before seeing oncologist with an excisional biopsy.

Should be referred: 'suspicion' implies no pathological diagnosis. You should be referred to a surgeon or interventional radiologist to biopsy a suspicious lymph node. If positive for lymphoma, referral to a hem/onc or rad/onc would ensue.