Will I lose my pre-/settled status if I travel for holidays? Will a visa be required for me to return to the UK?

No, you will not lose your pre/settled-status if you travel for holidays. With pre-settled status, you are able to stay outside the UK for up to 6 months in total in any 12-month period without breaking your continuous residence period in the UK. If you spend more than a total of 6 months in any 12-month period outside the UK, however, you will not be able to convert your pre-settled status to settled status (indefinite leave to remain). If you already have settled status, you can stay outside the UK for a period of up to 5 years without losing your status. (See also this FAQ on settled status 5-year absences)