How does a cleric multi-class spells work

[Sir cryosin]

As it says in the title I've played a few spellcasters but they've never been multi-class and I've never played a cleric but I was thinking about my next character a melee Focus Tempest cleric 1level dip and the rest storm sorcerer And for my attack I'll be using booming blade with a great sword then every now and then using my sorcery points to Quicken booming Blade 2 cast it again. But I'm getting off topic here anyways so with that one level cleric dip would I be able to have access to cleric levels up to my spellcasting level or am I only have access to first level clerics because I only have one level cleric

[Joe the Rat]

Only 1st level cleric. You prepare (or learn) spells by class level, and use the combined caster level for spell slots only.

[Vogonjeltz]

As it says in the title I've played a few spellcasters but they've never been multi-class and I've never played a cleric but I was thinking about my next character a melee Focus Tempest cleric 1level dip and the rest storm sorcerer And for my attack I'll be using booming blade with a great sword then every now and then using my sorcery points to Quicken booming Blade 2 cast it again. But I'm getting off topic here anyways so with that one level cleric dip would I be able to have access to cleric levels up to my spellcasting level or am I only have access to first level clerics because I only have one level cleric

It doesn't say in the title that you've played a few spellcasters.

The rules for multiclassing are found in Chapter 6 of the PHB, pages 163-165.

Short answer:

Progression in spell slots is a function of levels in spellcasting classes. All classes contribute.

Progression in spells known/list access is a function of levels in that particular class. Only the particular class contributes.