Hi Ka Man,
SA108 and SA109 are just two of the supplementary pages that are submitted with a completed self assessment tax return (SA100)
The supplementary pages cannot be used on their own, they can only be used in support of a tax return.
If you qualify for a split year then you only report any foreign income for the UK part of the year:
RDRM12000 - Residence: The SRT: Split year treatment: Contents
The guidance at RDRM12150 will help you work out if split year treatment applies.
If you do not qualify, then you will need to report all your foreign income to the UK:
Tax on foreign income