Signed off sick during probation period

I have just been signed off sick for 10 days due to bereavement and low mood.



I have been with my employer since July this year and last month my 3 month probationary period was extended for another 3 months due to having time off and making mistakes.



I don't have a contract of employment with them and I am now worried I may lose my job when I return to work in 10 days time.



If I do lose my job do I have any grounds for a claim against them?



Thanks,

Signed off sick during probation period