This is from a summary of PMD conditions in the 2001-5700kg bracket on On-Track's website. They're not good at quoting their sources so you might need to go dig into those yourself, but so far as I know it's legit.
You may fly an aircraft no greater than 5700 kg MTOM provided you do not suffer from any physical or mental condition or illness, or any history of such a condition or illness that might impair the safe operation of normal flight controls or render you unfit at any time to perform any function for which the licence is granted.
As a minimum, such conditions include:
a. any alcohol or drug abuse, addiction or misuse;
b. any neurological condition requiring medication;
c. any functional disability likely to impair safe operation of normal flight controls;
d. any recent surgery or new medical treatment;
e. any collapse, fainting (syncope), seizure or loss of consciousness;
f. any history of (a) to (e); or
g. other medical conditions specified by the UK CAA:
i. Being prescribed medication for any psychiatric illness;
ii.Bipolar disorder, schizophrenia or other psychotic illness, or a diagnosis of personality disorder;
iii.Dementia or cognitive impairment;
iv.Being prescribed medication or treatment for angina or heart failure;
v.Cardiac surgical procedures including coronary angioplasty or stenting and cardiac device implantation;
vi.Insulin treatment for diabetes;
vii. Chronic lung disease with shortness of breath on exertion.
If any of the above are present or you are unsure about the applicability of a condition, treatment or medication, you must consult with a UK CAA AME to discuss if these conditions, treatments or medications would prevent you making a medical declaration.
So if you're just trying to save money, you may be okay. If you have lost your class 1/2 for any medical reasons, the odds are against you.
G