We understand that you're feeling irritated and have financial concerns, but we want to remind you that God cares about every detail of your life. First, let's address the spiritual aspect of your request. It seems that you were to believe in yourself, but remember our belief and acceptance comes from Christ. We are encouraged in Philippians 4:13 WEB, "I can do all things through Christ who strengthens me." It is not belief in ourselves, but Christ who lives in us that will sustain us.
Regarding your financial needs, it's important to remember God's provision and promises. In Matthew 6:25-34 WEB, Jesus teaches us not to be anxious about our lives, what we will eat, or what we will wear. He reminds us that our heavenly Father knows that we need all these things. Instead, we are to seek first God's Kingdom and his righteousness, and all these things will be given to us as well. Also in Matthew 7:7 WEB, we are encouraged to "Ask, and it will be given you. Seek, and you will find. Knock, and it will be opened for you."
Instead of focusing on selling your paintings for exactly £400 to meet your bills, turn your focus to God, trusting that He will provide for your needs. God may have different plans for you than merely selling your paintings for financial provision. Look for the opportunities God is placing before you to use your gifts and talents for His glory.
Let's pray together:
"Father, we come before You, lifting up our brother/sister in Christ. We ask that You would ease the irritation and fill him/her with Your peace. Help him/her to cast all anxieties on You, knowing that You care for him/her. We pray for Your provision, that You would meet all of his/her needs according to Your riches in glory. Give him/her opportunities to use his/her artistic gifts for Your glory, and open doors for financial provision. Help him/her to be a good steward of the resources You have given him/her. Above all, draw him/her closer to You, that he/she may find complete satisfaction and joy in You. We ask this by the name of Jesus Christ, through whom we have access to the Father. Amen."
Remember, it is important to pray in Jesus' name, as it is through Him that we have access to God. As it says in John 14:6 WEB, "Jesus said to him, I am the way, the truth, and the life. No one comes to the Father, except through me." If you have not already, consider turning to Jesus as your Lord and Savior, believing in Him for the forgiveness of your sins and eternal life. This is a much better reason to believe in yourself, because you are a child of God.
Lastly, be reminded of Proverbs 30:7-9 WEB, Two things I have asked of you; dont deny me before I die: Remove far from me falsehood and lies; give me neither poverty nor riches; feed me with the food that is needful for me. Trust in God's provision for you.