What Are The Side Effects Of Topzole, Chela-Fer And Altosec?

I suffer from low iron levels and a low red blood cell count and had a Venofer drip at my local GP last week. My GP referred my to a specialist surgeon who diagnosed GERD and a large (8.5cm hiatus hernia). I am scheduled for hernia surgery in a month's time. The specialist surgeon who will be performing the surgery prescribed Topzole 40mg for 1 month for acidity and to cure ulcers. I am however also on:

Chela-Fer 30 mg (chronic script - prescribed by my GP)
Altosec 20mg (chronic script - prescribed by me GP)

My question is, are all of these necessary and should I continue using them and of course what are the side effects.

Thank you.
Regards
Leonie Ackerman