When declaring income and gains in a Self Assessment Tax Return, the figures declare are in whole pounds only. You can round up or down to a whole pound in your favour. You would not need to declare £0.10 as you can round this down to £0.00.
If you meet the critieria form split year treatment, you will need to register for self assessment to claim split year treatment. Otherwise, you would need to declare your world-wide income for the whole tax year which a tax return would also be required. Have a look at section 9 of RDR1, regarding the remittance basis and small amounts of foreign income.
Residence, domicile and the remittance basis: RDR1