Maths Gcse help and advice!

Hello everyone! I am currently in year 11 and I need to achieve a min grade 6 in maths for my GCSEs. I REALLY struggle with maths and get grades 4s and 3s most of the time. I obviously cannot do foundation as I cannot get higher than a 5 and I need the 6. all people tell me s practice practice practice. which i guess is true but i just dont know how??? like I'm guessing past papers but I keep getting nightmares of my math results only being a 5 and I really need a 6 and I won't be allowed to retake maths as I would have passed! does anyone have any advice they can give me and I'm scared that it is too late now and I won't manage to make a difference to my grades? BTW i do Edexcel maths and my school provide me with Hegarty maths. Many people tell me to basically do the whole of Hegarty maths and do past papers. Is that a good way of doing it? Any advice would be much appreciated!